1. Field of the Invention
The invention relates in general to a via hole structure and a manufacturing method thereof, and more particularly to a via hole structure and a manufacturing method thereof applied on the circuit design of the substrate.
2. Description of the Related Art
Printed circuit board (PCB) is an essential part of an electronic product. The PCB is manufactured by forming conductive circuit pattern such as copper foil on the surface or the inside of an insulating base by printing. The key function of the PCB is connecting the circuits of the relevant components.
The early design of printed circuit board is single-sided board. However, due to the restriction on the circuit design of single-sided board, double-sided board and multi-layer board are developed latter on. Double-sided board and multi-layer board have a larger substrate surface more adaptable to complicated circuit design. The paths of substrate are intercommunicated with a via hole passing through various layers so that the distribution of circuit between various substrates is connected thereby embody high density distribution of circuit. As the current electronic products are directed towards powerful functions and design of lightweight, compactness and slimness, the cost and complication of circuit design of the substrate will be reduced if the space utilization of the substrate is improved.
Please Refer to FIG. 1A and FIG. 1B. FIG. 1A is a top view of the inductance circuit design of a conventional printed circuit board. FIG. 1B is a side view of the inductance circuit design of a conventional printed circuit board of FIG. 1A. The conventional printed circuit board inductance circuit device 10 comprises a multi-layer board 11, a spiral inductance 12, and a via hole 13. The via hole 13 is used for connecting the printed circuit boards of a multi-layer board 11. The spiral inductance 12 is disposed on the surface of the multi-layer board 11 for generating inductance effect.